The present invention relates to wiring installations for electric devices for a nuclear reactor having a removable cover, devices such as sensors for measuring the position of the control clusters, actuators for these clusters, thermocouples, etc. The invention is particularly suitable, although not exclusively, for reactors cooled and moderated with light water having a large number of control clusters which could cause problems when defective cables are to be changed or during connection/disconnection operations on electric devices.
Wiring installations are already known for nuclear reactor electric devices. The documents FR-A-No. 2 567 305 corresponding to U.S. Pat. No. 4,683,106 (Jahnke) shows an installation of the type including for each of the electric devices, a plurality of first cable each extending from one of said devices and terminated with a first fixed connector located above the reactor cover and a plurality of second cables each corresponding to a respective first cable and each having two connectors at the ends thereof, one for disconnectable connection to one of the first fixed connector located above the cover and the other for disconnectable connection to a second fixed connector carried by a plate remote from the reactor vessel. The second cable has a first section placed inside a sealed sheath installed horizontally above the cover and a second section for connection to the second fixed connector carried by the plate remote from the reactor.
This wiring installation overcomes numerous problems. However, when opening the cover of the reactor, it is necessary to disconnect numerous cables and their respective sections for access to the inside of the vessel. On the contrary, when closing the cover, all these cables must be reconnected one by one with risk of error.
By way of example, for a known pressurized water nuclear reactor, having four cooling loops, the number of control and shut down clusters is 73 and the number of thermocouples 52. For each control cluster exists a cable for supplying power for the controlling mechanisms of the cluster and a measuring cable for the sensor measuring the position of the cluster. There is also one mesuring cable per thermocouple, which makes a total of 198 cables.
Installing these cables is a long, delicate operation carried out under difficult access conditions. In addition, the connection of the different connectors during operations for opening/closing the cover of the reactor is carried out in an hostile environment due to the core radioactivity.
In certain cases the cables must comply with high radii of curvature and the small amount of room available above the cover does not alow the presence of extra superfluous lengths. These must then be cut on the spot, under the difficult conditions mentioned above.
It is an object of the present invention to provide an improved wiring installation. It is a more particular object to provide a device which renders possible:
a reduction of time of intervention on the reactor, therefore improving the availability of the nuclear reactor for producing power, and a minimization of the irradiation of the working staff,
a lower deterioration of the cable connections of the wiring installation,
a reduction of the risk of errors during reconnection of the cables after intervention on the cover of the reactor or in case of changing a damaged cable.
For that purpose, the invention proposes in combination with a nuclear reactor having a vessel provided with a removable cover, a wiring installation for electrical connections of a plurality of devices of the nuclear reactor, comprising:
(a) a plurality of first multiwire cables each extending at least from certain ones of said devices and terminated with a first connector located above said cover at an end remote from said device,
(b) a plurality of second multiwire cables each for connection with a respective one of the first cables and each having:
(b.sub.1) a first section having at a proximal end thereof one second connector for disconnectable connection to one of said first connectors and at a distal end thereof a third connector, PA1 (b.sub.2) a second section having at a proximal end thereof a fourth connector for disconnectable connection to said third connector and at a distal end thereof a first multicables connector having a plurality of electrical contacts connected to respective wires of said second section, said first multicables connector being common to at least ten independent second sections, PA1 (b.sub.3) a third section having at a proximal end thereof a second multicables connector having a plurality of electrical contacts connected to respective wires of said third section and corresponding to respective wires of said second section, said second multicables connector being common to at least ten independent third sections corresponding to said independent second sections for removable connection to said first multicables connector, and at a distal end thereof a fifth connector for connection with a respective sixth connector fixed on a plate remote from the reactor vessel.
The presence of multicables connecors, able to be connected and disconnected quickly, reduce considerably the intervention time of operations of the reactor. The risks of error during reconnection are furthermore eliminated.
It is another object of the invention to provides a wiring installation, further comprising supporting means for the second multiwires cables having:
first sections supporting means comprising a plurality of rigid conduits arranged above the cover in a plurality of layers perpendicular to the axis of the reactor vessel, the conduits in each layer being parallel to each others, and,
conduits supporting means comprising a modular metallic structure supporting each one of said plurality of layers.
It is another object of the invention to provide a wiring installation wherein the supporting means for said second multiwire cables further comprise third section supporting means arranged for pivoting about one fixed pivot and supporting third sections of second multiwire cables corresponding to a natural number of second multicables conectors connected thereof. After disconnection of the multicable connectors and by causing the support means to pivot, the top of the cover may thus be readily freed.
In another advantageous embodiment, it could be made recourse to one of the following arrangements:
the rigid conduits are each formed with a sealed metallic duct for containing a plurality of first sections of second multiwire cables, said first sections being drowned into an isolating product resisting to radiations,
the first multiwire cables penetrate into corresponding rigid conduits through penetrations, said penetrations being regularly disposed on lateral surfaces of said conduits according to the position of the respective devices connected to said first multiwire cables,
each second connector is fixed on the surface of a corresponding conduit,
at least some of the second multiwire cables have their third connector fixed ona lateral surface of the corresponding conduit,
the first multicables connectors and the corresponding second multicables connectors are connectable and disconnectable automatically.